Uptake of ovalbumin-conjugated starch microparticles by pig respiratory nasal mucosa in vitro

Feasibility of chitosan-based nanoparticles approach for intranasal immunisation of live attenuated Japanese encephalitis vaccine

Intranasal (IN) administration, a non-invasive route, is explored to overcome the limitations of conventional subcutaneous (SC) injection for Japanese encephalitis (JE) immunisation. Mucoadhesive nanoparticles (NPs) are recognised for the benefits they offer via IN delivery, such as extended retention time of the vaccine on the mucosa. The purpose of this study was to evaluate immunisation effect of live attenuated Japanese encephalitis-chimeric virus vaccine (JE-CV)-loaded mucoadhesive NPs based on chitosan (CS) or chitosan maleimide (CM), a novel mucoadhesive polymer, via the IN route to improve the mucosal immunisation against JE. The results revealed that IN immunisation stimulated seroprotection following PRNT₅₀ evaluation. Moreover, compared with SC immunisation, IN immunisation in mice provided a higher sIgA level, leading to improved mucosal immune response. In addition, chitosan-based NPs showed an adjuvant effect on the IN vaccine due to their mucoadhesive and antigen-uptaken properties. CM NPs successfully induced sIgA. In contrast, SC JE-CV immunisation induced negligible mucosal immunity. These immunological advantages revealed that JE-CV-loaded mucoadhesive NPs are a promising approach for IN vaccination as an alternative route for JE protection due to the stimulatory effects on both mucosal and systemic immune responses.

Uptake and Transport of Ultrafine Nanoparticles (Quantum Dots) in the Nasal Mucosa

A wide variety of colloidal delivery systems, including polymeric nanoparticles, metal colloids, liposomes, and microemulsions have been reported to enhance the delivery of therapeutic agents across the nasal mucosa. The mechanisms involved in the uptake of these nanomaterials, especially ultrafine nanomaterials (diameters < 20 nm) through the nasal mucosa are not well understood. Fluorescent quantum dots (QDs) were used to investigate the uptake of ultrafine nanoparticles by bovine respiratory and olfactory mucosal tissues following in vitro exposure, and an inductively coupled plasma optical emission spectroscopy method was developed to quantify the amount of QDs localized within the tissues. QDs do not biodegrade or release their core materials and, as a result, this method allowed for the direct quantification of the nanoparticles themselves, rather than the measurement of a potentially dissociated drug or label. The results demonstrated that carboxylate-modified QDs (COOH-QDs) showed ∼2.5-fold greater accumulation in the epithelial and submucosal regions of olfactory tissues compared to that in respiratory tissues. Endocytic inhibitory studies showed that clathrin-dependent endocytosis, macropinocytosis, and caveolae-dependent endocytic process are all involved in the uptake of COOH-QDs into the respiratory tissues. In olfactory tissues, clathrin-dependent endocytosis is the major endocytic pathway involved in the uptake of COOH-QDs. Additional energy-independent pathways also appeared to allow the transfer of COOH-QDs within the olfactory mucosa. When polyethylene glycol-modified QDs known as PEGylated QDs (PEG-QDs) of similar size, ∼15 nm, were investigated, no nanoparticles were detected in the tissues suggesting that the PEG corona limits the interactions with endocytic and other uptake processes in the nasal epithelium. The capacity for nanoparticle uptake observed in the nasal mucosa, along with the ability of significant numbers of nanoparticles to enter the olfactory tissues using nonenergy-dependent pathways show that the pathways for ultrafine nanoparticle uptake in the nasal tissues have both drug delivery and toxicologic consequences. This places an increased importance on the careful selection of nanoparticle components and drugs intended for intranasal administration.

Evaluation of neuropeptide loaded trimethyl chitosan nanoparticles for nose to brain delivery

Leucine-enkephalin (Leu-Enk) is a neurotransmitter or neuromodulator in pain transmission. Due to non-addictive opioid analgesic activity of this peptide, it might have great potential in pain management. Leu-Enk loaded N-trimethyl chitosan (TMC) nanoparticles were prepared and evaluated as a brain delivery vehicle via nasal route. TMC biopolymer was synthesized and analyzed by (1)H NMR spectroscopy. TMC nanoparticles were prepared by ionic gelation method. Mean peptide encapsulation efficiency and loading capacity were 78.28±3.8% and 14±1.3%, respectively. Mean particle size, polydispersity index and zeta potential were found to be 443±23 nm, 0.317±0.17 and +15±2 mV respectively for optimized formulations. Apparent permeability coefficient (Papp) of Leu-Enk released from nanoparticles across the porcine nasal mucosa was determined to be 7.45±0.30×10(-6) cm s(-1). Permeability of Leu-Enk released from nanoparticles was 35 fold improved from the nasal mucosa as compared to Leu-Enk solution. Fluorescent microscopy of brain sections of mice showed higher accumulation of fluorescent marker NBD-F labelled Leu-Enk, when administered nasally by TMC nanoparticles, while low brain uptake of marker solution was observed. Furthermore, enhancement in brain uptake resulted into significant improvement in the observed antinociceptive effect of Leu-Enk as evidenced by hot plate and acetic acid induced writhing assay.

Drug delivery to inflamed colon by nanoparticles: comparison of different strategies

For inflammatory bowel disease (IBD) treatment, local delivery of molecules loaded in nanoparticles to the inflamed colon could be a promising strategy. The aim of this study was to investigate how drug-loaded polymeric nanoparticles target the site of inflammation and to analyse the influence of different colon-specific delivery strategies. Three different polymeric nanoparticles were formulated using ovalbumin (OVA) as a model drug. pH-sensitive nanoparticles were made with Eudragit(®) S100. Mucoadhesive nanoparticles were created with trimethylchitosan (TMC). A mix of polymers, PLGA, PEG-PLGA and PEG-PCL, were used to obtain a sustained drug delivery. Furthermore, ligands targeting immune cells (i.e. mannose) or the inflamed colon (i.e. a specific peptide) were grafted on the PEG chain of PCL. Interaction of nanoparticles with the intestinal epithelium was explored using Caco-2 monolayers designed to mimic an inflamed epithelium and then visualized using confocal laser microscopy. TMC nanoparticles had the highest apparent permeability for OVA in the untreated model. However, in the inflamed model, there were no difference between TMC, PLGA-based and Eudragit(®) nanoparticles. The uptake of nanoparticles in the inflamed mouse colon was assessed in a horizontal diffusion chamber. Mannose-grafted PLGA nanoparticles showed the highest accumulation of OVA in inflamed colon. Based on these results, active targeting of macrophages and dendritic cells may be a promising approach for targeting the colon in IBD.

Targeting the porcine immune system--particulate vaccines in the 21st century

During the last decade, the propagation of immunological knowledge describing the critical role of dendritic cells (DC) in the induction of efficacious immune responses has promoted research and development of vaccines systematically targeting DC. Based on the promise for the rational design of vaccine platforms, the current review will provide an update on particle-based vaccines of both viral and synthetic origin, giving examples of recombinant virus carriers such as adenoviruses and biodegradable particulate carriers. The viral carriers carry pathogen-associated molecular patterns (PAMP), used by the original virus for targeting DC, and are particularly efficient and versatile gene delivery vectors. Efforts in the field of synthetic vaccine carriers are focussing on decorating the particle surface with ligands for DC receptors such as heparan sulphate glycosaminoglycan structures, integrins, Siglecs, galectins, C-type lectins and toll-like receptors. The emphasis of this review will be placed on targeting the porcine immune system, but reference will be made to advances with murine and human vaccine delivery systems where information on DC targeting is available.

Mathematical modeling of molecular diffusion through mucus

The rate of molecular transport through the mucus gel can be an important determinant of efficacy for therapeutic agents delivered by oral, intranasal, intravaginal/rectal, and intraocular routes. Transport through mucus can be described by mathematical models based on principles of physical chemistry and known characteristics of the mucus gel, its constituents, and of the drug itself. In this paper, we review mathematical models of molecular diffusion in mucus, as well as the techniques commonly used to measure diffusion of solutes in the mucus gel, mucus gel mimics, and mucosal epithelia.

Starch Microparticles as Oral Vaccine Adjuvant: Antigen-dependent Uptake in Mouse Intestinal Mucosa

An oral vaccine formulation comprised of starch microparticles with conjugated antigens is being developed. In this report we have examined the uptake of such microparticles by the intestinal mucosa and examined whether the conjugated antigen can influence the uptake. Two model antigens were used: recombinant cholera toxin B subunit (rCTB), which is known to bind to the ubiquitous GM1-receptor, and human serum albumin (HSA) which is not known to have any specific binding properties. The uptake was studied in mouse ligated intestinal loops into which the microparticles were injected. The intestinal loops were excised, fixed in ice-cold 95% ethanol. Entire specimens were mounted, exposed to fluorescence-labeled reagents staining the cytoskeleton, the particles and/or M cells and examined in a confocal laser-scanning microscope. A qualitative difference in the uptake of the rCTB- and HSA-conjugated microparticles was seen. The rCTB-conjugated microparticles were found both in villi and in the follicles of the Peyer's patches. HSA-conjugated microparticles could only be detected in the follicles of the Peyer's patches and not in villi. The rCTB conjugated to the microparticles did not lose its ability to bind the GM1-receptor, as shown with a GM1-ELISA, and the uptake of rCTB-conjugated microparticles in villi is most probably facilitated by the rCTB binding to the GM1-receptor. The qualitative difference in uptake could be of importance for the development of an immune response as the cytokine and chemokine microenvironment during antigen presentation will decide the differentiation of the immune response induced.

Rat, ovine and bovine Peyer's patches mounted in horizontal diffusion chambers display sampling function

Freshly excised rat, ovine and bovine ileal Peyer's patch (PP) and non-Peyer's patch tissues (NPP) were mounted in modified horizontal polyethylene diffusion chambers with a range of window areas. Rat tissue was initially used to establish that barrier function and histology were maintained for up to 60 min. Horse-radish peroxidase (HRP) fluxes and S. Typhimurium adherence and invasion were significantly higher in rat PP over NPP. Particle uptake was shown to be a rapid, energy-, time-, and size-dependent process, occurring more readily in PP than NPP tissue in each species. In a kinetic analysis, particles were localized initially in the follicle-associated epithelium and then in the dome region. For NPP uptake, particles were initially localized to villous epithelium, and were then detected in the crypts and lamina propria. Electrophysiological parameters including pharmacologically-stimulated inward short-circuit current responses were determined in isolated PP and NPP from each species mounted under identical conditions in Ussing chambers. In conclusion, comparative functional and histological characteristics of PP from several species were demonstrated in horizontal diffusion chambers. Horizontal diffusion chambers are therefore a useful in vitro model in which a range of functions including transport of particulate formulations by PP may be examined.

Starch microparticles as vaccine adjuvant

The demand for new vaccine adjuvants is well documented. New purified antigens from parasites, bacterial or viral pathogens, as well as recombinant subunit antigens and synthetic peptides, are often inherently weak immunogens; therefore, they need some kind of adjuvant to help initiate an immune response. In addition, there are very few adjuvants using the potential of the mucosal immune system, which may play an important role in the defence against air- and food-borne infections. Starch is a natural biocompatible and biodegradable polymer that is suitable for the production of various particulate adjuvant formulations, which can induce mucosal as well as systemic immune responses. This review gives an account of the different starch adjuvants used in immunisation studies. In particular, the properties of polyacryl starch microparticles as an oral vaccine adjuvant that induce protective immune responses in mice challenge experiments are summarised. In addition, a diphtheria booster vaccine has been proposed to be used to proving the concept in man and the possibilities to design an efficient vaccine formulation for human use are discussed.

Preparation and characterization of a biodegradable drug targeting system for anticancer drug delivery: microsphere-antibody conjugate

Targeted delivery of anticancer drugs is one of the most actively pursued goals in anticancer chemotherapy. A major disadvantage of anticancer drugs is their lack of selectivity for tumour tissue, which causes severe side effects and results in low cure rates. Any strategy by which a cytotoxic drug is targeted to the tumour, thus increasing the therapeutic index of the drug, is a way of improving cancer chemotherapy and minimizing systematic toxicity. This study covers the preparation of the gelatin microsphere (GM)-anti-bovine serum albumin (anti-BSA) conjugate for the development of a drug targeting approach for anticancer drug delivery. Microspheres of 5% (w/v) gelatin content were prepared by crosslinking with glutaraldehyde (GTA) at 0.05 and 0.50% (v/v) concentration. Microspheres were in the size range of 71-141?microm. The suitability of these microspheres as drug carriers for anticancer drug delivery was investigated in vitro by studying the release profiles of loaded methotrexate (MTX) and 5-fluorouracil (5-FU) and the cytotoxicities on cancer cell lines. The in vitro MTX release profiles (approximately 22-46% released in 24 h depending on the amount of GTA used) were much slower compared to 5-FU (approximately 42-91% released in 24 h). Both drugs demonstrated an initial fast release, which was followed by gradual, sustained drug release. The MTT cytotoxicity test results of GMs loaded with 5-FU and MTX showed approximately 54-70% and approximately 52-67% cytotoxicities in 4 days. In general, incorporation of MTX and 5-FU in microspheres enhanced the cytotoxic effect in a more prolonged manner compared to the free drugs. Gelatin micospheres were chemically conjugated to anti-BSA and the antigen-antibody activities were studied by immunofluorescence. Results indicated approximately 80% binding with conjugated anti-BSA and BSA-FITC. Based on their low cytotoxicity and the high antigen binding efficiencies, anti-BSA conjugated gelatin microspheres could be suitable targeted drug carrier systems for selective and long-term delivery of anticancer drugs to a specific body compartment (i.e. bladder cancer).

Mucosal vaccination against diphtheria using starch microparticles as adjuvant for cross-reacting material (CRM197) of diphtheria toxin

Mucosal vaccination has the advantage of eliciting a local mucosal immune response as well as a systemic response. In this investigation, polyacryl starch microparticles were conjugated to diphtheria toxin cross-reacting material (CRM197) as a mucosal adjuvant for oral or intranasal immunisation of mice. Various methods of stabilising CRM197 with formaldehyde were investigated. A good systemic and local mucosal immune response was attained with oral immunisation when CRM197 was treated with a relatively low formaldehyde concentration prior to conjugation to the microparticles. No immune response was seen after intranasal immunisation.